Effusion (Medical Fluids) (definition of)

An effusion is medically defined as an "abnormal accumulation of fluid." In the case of mesothelioma patients, this takes place in the pleural space, which restricts the lungs from expanding.

Pleural effusion is not a disease, but rather a symptom of some pathological condition of the respiratory system.

The Mesothelium

The body's internal organs are covered by a self-lubricating membrane, called the mesothelium. The part of this tissue that covers the lungs is called the pleura, or pleural lining. This is consists of an inner layer covering the surfaces of the lungs proper, and an outer layer lining the rib cage and diaphragm. The lubricative fluid is produced by the lymphatic system.

The body's lymphatic system is capable of draining as much as 300 ml. of fluid at any given time. However, when more of this fluid is produced than the lymphatic system can absorb, pleural effusion is the result. As this fluid builds up, it exerts pressure on the lungs, preventing them from expanding properly.

Types of Pleural Effusion And Their Pathology

Different types of pleural effusion include:

Pyrothorax: caused by a bacterial infection, the fluid consists of a mixture of proteins and dead white blood cells, the by-product of inflammation and immune system reaction

Hemothorax: a build-up of blood in the chest cavity due to trauma (injury)

Chylothorax: in most cases, a symptom of Hodgkin's Disease (cancer of the lymph nodes

Pneumothorax: a complete collapse of the lung due to pleural effusion

Hydrothorax: a general term for the buildup of any bodily fluid in the chest cavity

A pleural effusion may be due to an unrelated cause, in which case it is known as transudate, or a respiratory condition directly, which is labeled exudate. The latter kind is a common symptom of lung cancer and mesothelioma.

Symptoms and Diagnosis

Although all respiratory ailments share the same symptoms - coughing, chest pain, shortness of breath - accurate diagnosis usually requires testing, which in some cases can be invasive.

Treatments

All effusions, whether pleural, peritoneal or affecting another part of the body must be drained in order for the patient to experience relief. In the case of pleural effusion, this involves a procedure called pleurodesis (for peritoneal conditions, it is called parecentesis). The physician will actually insert a tube into the patient, allowing fluids to drain into a bag or other container. The procedure may take anywhere from two to forty-eight hours.

In this procedure, the patient sits on a chair or the edge of a bed and leaned forward in order to expose the upper back. Typically, the physician will mark the side of the chest where the drain is to be inserted, cleanse the area with antiseptic and inject a local anesthetic.

Once this has been done, the physician will make a small incision and insert a needle known as a cannula. This is essentially a hollow steel tube cut at an angle and attached to a flexible plastic tube (also used for I.V. and intravenous feeding). This tube is attached to a drainage bag or bottle into which the fluid is collected.

The length of time required for this procedure varies, depending on how much fluid must be drained; this may be anywhere from a few minutes to two days. As the rate of flow lessens and the physician determines most of the fluid has been removed, s/he will order an x-ray to ensure the lung is again functioning properly.